Automotive emissions are reduced substantially through the use of engine exhaust catalytic converters in vehicles. A catalytic converter can be damaged, however, if misfire occurs in one or more cylinders of the engine. A misfire could be caused by a number of events, for example, by a broken or disconnected wire in the vehicle ignition or injection systems. When a misfire occurs, unburned fuel may enter the catalytic converter from the misfiring cylinder and may cause reaction temperatures within the converter to increase sharply. Such increases can lead to overheating and damage of the catalytic converter.
In recently manufactured vehicles, misfire typically can be detected and diagnosed. A warning light may be activated if misfire occurs above a threshold level. It would be desirable to make use of misfire detection and diagnostics to protect the catalytic converter.